Centrifugal casting machine and method of casting



Oct. 30, 1934. w. D. SARGENT ET! AL CENTRIFUGAL CASTING'MACHINE AND METHOD OF CASTING Fild Jfily 2, 19:1 2 Sheets-Sheet 1 MMam 06hr hfllz'awz J. a

I d'An/Y Oct. 30, 1934. w. D. SARGENT El AL CENTRIFUGAL CASTING MACHINE AND METHOD OF CASTING Filed July 2. 1931 2 Sheets-Sheet 2 WWO: hir'llimm 0. 6221' M'lll'am 1?. 6612910,

B 52 age 7 @3 ATTORNEYS Patented Oct. 30, 1934 PATENT OFFICE CENTRIFUGAL CASTING MACHINE AND METHOD OF CASTING William D. Sargent, New York, N. Y., and William A. Geisler, Newark, N. J., assignors, by mesne assignments, to-Durafer (Inc.), Dover, Del., a

corporation of Delaware Application July 2, 1931, Serial No. 548,276

4 Claims.

This invention relates generally to the centrifugal casting of articles about a core which is removed to provide a central recess within the article. More particularly, it. is concerned with 5 casting of such articles in which a recess extends less than the entire length of the article as is the case, for instance, in artillery shells. The principal object of the invention is to provide an improved method of casting such articles in accordance with which a metal structure of superior properties is attained while substantial economies are eiiected.

In accordance with the invention the metal is introduced into the mould in a cylindrical stream which itself is whirling and permitted to build up progressively about the core, the speed of rotation of the mould being so controlled that the core is not injured and the metal will be deposited progressively from the outer wall inwardly and upwardly until the mould is filled, the rate of pouring being such as to result in the desired distribution of metal and its subsequent cooling in such stages as will insure a dense homogenous structure. The cooling will take place from the outside of the casting inwardly and from the lower portion upwardly. However, the overall time for casting is considerably reduced with resulting economies as compared to known methods.

One of the principal objects of the present invention is to provide an improved method of casting and apparatus therefor in which the metal is introduced into the mould in a circular whirling stream. -This object is accomplished by pouring the metal into the mould through a conical gate disposed concentrically to the axis of rotation of the mould but receiving metal from a source of supply which is disposed eccentric. to said axis.

A further object of the invention is to provide for the control of the entering stream of metal so that it may be caused to impinge on the walls of the mould at any desired distance from the gate.

A further object of the invention is to provide a sectional mould with which the improved method may be conveniently practiced, the parts of the mould being separable to permit the ready removal of the casting.

A further object of the invention is to provide simple apparatus for accomplishing the stated purposes with substantial economies.

The invention will be more fully described in connection with the apparatus shown in the ac- I companying drawings which is intended merely to exemplify suitable means for practicing the improved method, and in which drawings:

Figure l is a view in vertical section taken on the plane indicated by the line l1 of Figure 2 through the improved apparatus, one section of the mould being removed in the interest of clearness.

Figure 2 is a view in vertical section taken on the apparatus illustrated in Figure 1 on the plane of the line 2 2 in Figure l, the exterior of the mould being shown in elevation.

Figure 3 is a view in horizontal section through the mould taken on the plane indicated by the line 33 of Figure 1.

Figure 4 is a fragmentary detailed view partly in section showing one of the supporting standards for the mould sections.

The apparatus illustrated includes a circular plate a which supports the mould and is journaled rotatably on rollers b which are preferably of such form and so disposed as to most eifectively support the plate and resist lateral thrust. These rollers may be mounted within a pit (2' so that the plate a is flush with the working surface 0. A circular guard a may be carried at the periphery of the plate a to prevent metal or other foreign matter entering the pit. 8

The plate a in the illustrated embodiment is formed with a depending circular flange a on which may be secured a ring gear d with which meshes a driving pinion 2 carried on a vertically disposed shaft e to which is secured a gear 2 meshing with a pinion f on the motor shaft 1' of a driving motor F. The motor I is supported movably within the pit as by ways g and may be moved conveniently by suitable operating mechanism illustrated as shafting f geared to a verti- 9o cally disposed operating shaft 1 having a hand crank f at its upper end whereby the operator may conveniently shift the motor onits ways. This adjustment is provided to permit the gears f and e to be changed as desired to change the gear ratio and subsequent speed of rotation of the plate a.

-The plate a is formed with a central opening a and a raised hub a concentric with the axis of rotation. On the plate may be supported a core plate 71. having a central opening it to receive the hub a and thereby center the core. The drawings illustrate a suitable sand core 2' carried on the plate It for use in casting a large shell. The core itself is disposed concentric with the core plate It and thus, during the casting operation, is concentric with the axis of rotation of the plate a.

With all of the parts described in the proper relationship it remains to provide a suitable mould. Such a mould is shown as consisting of two parts k, is, having cooperating grooved meeting edges. k to insure a tight union when the parts are secured together. Lugs k engaged by bolts k serve as a means for securing the mould sections together when casting is to be done. The lower edges of the mould sections k, k, are formed with semi-circular flanges W, the interior faces of which are preferably tapered to embrace snugly complementary tapered sections on the periphery of the core plate It.

While it will be understood that the invention is not to be limited to the'details of construction of themould nor its supporting and controlling mechanism the drawings shown one practical arrangement. The retaining lugs k are formed with laterallyextending arms k mounted slidably in supporting brackets I carried by the table a. Bearing plates 12 may be mounted within the ways provided by the brackets Z and engage the arms k adjustment for the bearing plates being provided in the form of set screws m. This construction insures a smooth shifting of the two mould halves and prevents a raising of the mould from the core plate h.

The mould sections may be separated after the casting is completed by any suitable mechanism. That illustrated consists of operating screws 0 secured to lugs k? on the respective mould sections and having hand wheels 0' for rotation of the screws in fixed standards p carried on the.

table a. By means of the hand wheels 0' the mould sections may be readily drawn apart or urged together, as will be understood.

Interiorly, the moulds are of such configuration as is to be given to the exterior of the article to be cast. Provision is made at the upper end thereof for supporting a conical gate q, the axis of which is concentric with the axis of rotation of the table a. The lower end q of the gate is of the diameter of the upper open end of the interior of the mould proper.

Any suitable means may be employed for pouring the metal into the gate q, a suitable stationary funnel being illustrated somewhat schematically at r. In accordance with one of the important objects of this invention, however, the metal from the source of supply is introduced into the gate at a point eccentric to the axis of rotation of the mould. I

, The improved method of casting will now be described in connection with the apparatus illustrated. With the parts in the described relationship for casting the plate a will be rotated by the motor at the necessary speed to give the condition to be referred to. The metal from the stationary source of supply 1' will pass into the gate q eccentric to the axis of rotation of the mould. This will impart to the metal initially a whirling motion within the gate. When the metal passes .through the constricted mouth of this tapered gate into the mould it will take the form of a circular whirling stream as indicated by the dash lines in Figure 1. It is preferable that this stream shall not be directed immediately against the .interior wall of the mould but shall impinge on it at a substantial distance below the upper end. The point of contact in accordance with the improved method can be controlled partly by the factor of the speed of rotation and partly by the form and dimensions of the gate q. The metal constituting the circular whirling stream will encircle the central core 1 and pass down the wall of. the mould to the bottom. At that point it begins to build up progressively filling the space between the wall and the core but not exerting directly on the core such stresses as might tend to fracture it. This condition can also be controlled by the speed of rotation and it will be found desirable not to impart to the stream of metal such velocity as will injure the core or prevent the uniform building up of the metal. After the core is completely immersed, however, the speed of rotation of the mould may be increased appreciably as well as the rate of pouring so as to complete the casting at the upper end in a short space of time. The cooling of the metal will take place from the surface of the casting inwardly as is desirable and from the bottom upwardly, the relatively greater mass above the core being the last to cool and set. After the pouring is completed rotation of the table a is stopped. As soon as the metal has cooled and set sufliciently the mould sections may be separated and the casting removed from the plate a. The apparatus is then ready for another core plate and core and another pouring.

The resulting article will be found to be constituted of metal with superior properties regardless of the metal that may be used. The method of introducing the metal into the mould while rotating the latter insures a dense homo-, geneous structure with a relatively tough skin, the density at the outer surface being relatively greater, as is desirable. The casting can be carried on with great facility using the permanent mould and substantial economies effected. Considerable control over the characteristics of the article cast is afiorded.

Changes in the details of construction of the apparatus will suggest themselves to one skilled in the art but all such changes are to be deemed within the scope of the invention so long as they fall under the appended claims.

What we claim is:

1. A casting machine comprising a mould, a core concentric therewith, means to mount the mould and core rotatably on the same vertical axis, and means to pour metal into the mould in a whirling inverted parabolic stream, whereby to protect the core and mould from direct impingement of the metal when poured.

2. A casting machine comprising a rotatable base, a sectional mould thereon, a core within the mould, said core and mould being disposed on the axis of rotation of the base, means to whirlingly deliver metal into the central portion of the mould at its top whereby the metal may be slightly centrifugally thrown and descend in the annular space between core and mould without directly impinging thereupon, and means to separate the sections of the mould to expose the completed casting.

- 3. The method of casting a hollow shell centrifugally about a'vertical axis which consists in mounting a core and a mould concentrically on a rotatable base with the axis of the core and mould on the axis of rotation, delivering metal into the top of the mould through a conical gate, pouring metal into the gate at a point eccentric to the axis of rotation, and rotating the gate at a speed to produce a circular whirling stream having sufficient centrifugal force to spread the stream and prevent it from directly impinging on the core, but not rotating so fast as to cause the stream to impinge upon the upper interior of the sectional mould.

4. The method of casting a hollow shell centrifugally about a vertical axis which consists in mounting a core and a mould concentrically on the core, but not rotating so fast as to cause the stream to impinge upon the upper interior of the sectional mould, and subsequently after filling the mould increasing the rotation speed thereof.

WILLIAM D. SARGENT. WILLIAM A. GEISLER. 

